This invention relates to a noise reducer using a recursive digital filter.
It is known to use recursive digital filters to reduce noises in video signals. Such recursive noise-reducers are based on the correlation between frames of the video signals.
In the MUSE (Multiple Sub-Nyquist Sampling Encoding) transmission system for high-quality (or high-definition) television (Hi-Vision), a luminance signal (Y signal) has a recursive period corresponding to two frames. Accordingly, recursive noise-reducers for the MUSE system are designed so as to operate on the basis of the correlation between frames separated at two-frame intervals. Such noise-reducers tend to have inadequate effects since the correlation between frames separated at two-frame intervals is relatively less existent.